This invention relates to ignition systems and methods.
High energy ignition systems are usually of the capacitor discharge kind where electrical energy is stored in a capacitor and is then rapidly discharged to an igniter or spark plug, producing an intense spark sufficient to ignite a fuel-air mixture. A solid state igniter may require a voltage of up to about 2000 volts to ensure reliable ignition in a gas-fuelled or oil-fuelled turbine. Once the flash has occurred, the voltage collapses to near zero while a large current flows, commonly in excess of 1500 amps, for the duration of the spark, until the energy stored in the capacitor has been dissipated. Various different arrangements are used to perform the switching operation by which the charged capacitor is connected to the igniter. For example, gas discharge tubes can be used, but these are bulky, expensive and can be delicate. Solid state switches, such as thyristors, have various advantages in that they are robust, compact and easily controlled. One problem with solid state switches is that those capable of handling very high voltages and currents are very expensive.